Honestly I think that all music by Capcom is fantastic - Any Megaman, Megaman X, Phoenix Wright, Street Fighter etc. Castlevania is a must have for me as well. I really love a lot of Final Fantasy stuff that isn't J-pop, rather very peaceful type arrangements (try Sight of Spira, FF10 disc 1).
Also, I really appreciate metal music, and I think that Daisuke Ishiwatari does some really cool music if you can get your hands on his stuff. He does the Guilty Gear/BlazBlue/Hardcorps type stuff. It's anime style gaming with a couple of poppy songs, but a lot is just hard rock. I could go on, but that will be my 2 cents for now.

Honestly, if you're in to "weirder" stuff (or at least, the non poppy-sounding), you cannot go wrong with ZUNTATA.

They made some of the best and most progressive game music back in the late 80s and 90s.
Stuff like Tamaya Kawamoto's work on Rayforce and RayStorm (good danceable tracks), OGR's surreal masterworks in Darius Gaiden and G-Darius, Yasuhise Watanabe's jazzy synth-work in Metal Black and Border Down (though that last one is after Zuntata broke up... oh well it still counts)...